I wrote last November about the dangers of cherrypicking out figures in crossbreaks to come up with sensationalist stories that don’t actually reflect the truth – and I spend an inordinate amount of time nagging about not paying too much attention to regional crossbreaks. Nevertheless, they never seem to go away.

On Friday, for example, the New Statesman was getting overexcited about the crossbreak for under 25s in the most recent YouGov poll, which showed Labour 47 points ahead of the Conservatives amongst young people. The figures were based on a sample of only 71 people, so the margin of error was about 12 points (in fact, given that the figures were re-percentaged to exclude Don’t knows and Won’t Votes it was actually even lower – only 45 people under 25 actually gave voting intentions, giving a margin of error of plus or minus 15 points.)

If the New Statesman had taken the time to look at other recent cross-breaks for young people it should have become clear that (a) the figures were very volatile, as you’d expect from such a small sub-sample and (b) that this was an outlier. The average figure for the rest of the last week was CON 24%, LAB 49%, a lead a little over half of Friday’s (this is still a very large Labour lead of course, but not unsurprising given they have a 12 point lead nationally and there tends to be a correlation between age and voting intention, with young people more Labour and older people more Conservative).

Another example this week was David Skelton at Platform 10, citing regional cross-breaks from Populus polling to demonstrate that support for gay marriage isn’t just amongst a metropolitan elite, but is actually higher in blue-collar Northern areas. Now, while I suspect David’s ultimate argument is correct (after all, it’s not like only Southern middle class people are gay or get married), the evidence he cites doesn’t really hold up. 81% of respondents in the North East did indeed tell Populus that they supported gay marriage… but it was on a sample size of 45 people, giving a margin of error of 15 points and meaning support for gay marriage in the North East was not actually significantly different to that in London.

Here’s what to remember about cross-breaks

1) Cross breaks often have small sample sizes and are not internally weighted.They are hence very volatile and imprecise, especially for things like age and region where some sample sizes are below 100, and very little weight should be given to them. For a sample size of 200 the margin of error rises to plus or minus 7 points, for 100 it rises to plus or minus 10 points.

2) Where you have a regular tracker such as the YouGov daily poll, the sheer volume of data means it is inevitable that volatile crossbreaks with large margins of error will sometimes produce results that look extreme. However odd these look, unless there is a sustained pattern they are not meaningful. If the actual figure is 50%, but you’ve only got 70 respondents, then you ARE sometimes going to get results showing 62% or 38%… purely from random variation.

3) All this goes double or triple for voting intention polls! For most polls the precise figures don’t matter – it is much the same story if 30% of people support a policy as if 40% do. In contrast, there is a world of difference between Labour being at 30% and Labour being at 40%. When it comes to voting intention, crossbreaks in a single poll should basically be ignored.

A couple of months ago Lewis Baston asked me an interesting question on Twitter. Given that regional cross-breaks on polls are so consistently misrepresented and misunderstood, should pollsters publish them at all? It does make me ponder. My starting point is always that it is good for pollsters to be as transparent as possible, unless there is a good reason not to be open, we should be.

Some crossbreaks are very useful in understanding and interpretting polls – think, for example, of how much voting intention cross-breaks help our understanding of leader approval ratings, best PM figures or my bete noire of “would policy X make you more likely to vote Y” questions. Sometimes they do show interesting things (look, for example, at the huge gender contrast you find in polls on nuclear power or nuclear weapons), or many issues where there is a clear correlation with age. Regional cross-breaks are, admittedly, less obviously useful but there are many instances when cross breaks are extremely beneficial to our understanding of polls if looked out as crude indicators of trends and correlations, rather than taken out of context.

I wouldn’t want to see pollsters stop giving out data, even data of limited use, for fear of it being misunderstood. The solution is really for political journalists to better understand polling and statistics. Some people will always misunderstand or misrepresent polls…but political journalists shouldn’t, they are too important a part of politics today.

Tonight’s YouGov poll for the Sun has topline figures of CON 31%, LAB 43%, LDEM 9%, UKIP 8%. It’s a twelve point lead, following on from another twelve point lead the day before. It looks as though the post-Jubilee feel good effect has now faded entirely and we are back to the 12 point Labour leads that YouGov’s daily poll have been averaging around for most of the time since the local elections.

There is also a new Opinium poll out today, with almost identical figures to YoGov’s. They have topline voting intention figures of CON 31%(+1), LAB 42%(+1), LDEM 9%(nc), UKIP 8%(-2). Changes are from their previous poll a fortnight or so ago.


Ipsos MORI have published their monthly political monitor for the Evening Standard. Topline voting intentions, with changes from last month, are CON 31%(-2), LAB 40%(-3), LDEM 10%(+1), Others 19%(+4) (including Greens on 5% and UKIP on 6%).

Other questions suggest a sharp fall in the public’s regard of George Osborne, something that YouGov also picked in polling since the budget. Asked who will make the best Chancellor Ed Balls now leads Osborne by 37% to 29%, compared to the two men being pretty much neck and neck the last two times MORI asked the same question in March 2011 and March 2012. The change is almost entirely down to Osborne’s falling ratings, while Ed Balls’s ratings have remained very stable.

The Conservatives brief post-Jubilee recovery seems to have passed. After a month of YouGov’s Labour leads averaging at twelve points last week we saw three polls in a row with leads down into single figures, enough to suggest it was more than mere sample variation.

However, today’s poll has Labour’s lead springing right back up again, with topline figures of CON 31%, LAB 45%, LDEM 9%, UKIP 9%. While it’s possible that this lead could be an outlier and we’ll see smaller leads again tomorrow, it makes a lot of sense that the lead should return to its pre-Jubilee position. The fact that there were some Jubilee celebrations may have made people feel generally better about the ways things are going or taken minds off the government’s problems, but the fundementals hadn’t changed.

The Times today leads with a Populus poll showing that 82% of people would like a referendum on Britain’s membership of the European Union.

This does not surprise me. Referendums are popular per se, whatever the subject asked about, people will support having a referendum on it. I have only ever seen one poll that has asked a straight question about holding a referendum on a subject and found that people don’t want one – and that was on the monarchy where the overwhelming majority of people support the status quo.* I expect if you found something dull, obscure or procedural enough you might find a another topic on which people would oppose a referendum, but certainly on almost any subject important enough for people to seriously suggest a referendum there is overwhelming support for having one.

If you stop to think about it, it is exactly what you’d expect. People hold politicians in extremely low esteem and asking if they would like a referendum on a subject is pretty much asking “Would you like a say on this subject, or would you like politicians to decide for you?”

That said, the actual question that Populus asked was more nuanced than that, starting to get at the more interesting question of whether a referendum on Europe is something people thought should be a priority right now. As well as support and opposition, Populus gave people the chance of agreeing in principle with a referendum, but saying now was not the time. The detailed results were 18% opposed to a referendum, 33% agreeing in principle, but saying now is not the right time, and almost half – 49% – saying that there should be a referendum on Europe now.

*UPDATE: Thanks to Pablo’s comments below, I have actually found a poll that showed the public opposed to a referendum on something! Eleven years ago in 2001 MORI asked if people wanted a referendum on the monarchy, 40% did, 51% did not.